1. Field of the Invention
The present invention relates to treating waste water and more particularly refers to a new and improved process for decontaminating process waste waters contaminated with radioactive isotopes.
2. Description of the Prior Art
In the manufacture of uranium dioxide powder from uranium hexafluoride and uranyl nitrate, such as described in detail in German Pat. Nos. 1 126 363, 1 592 477 and 1 924 594, as well as in German Published Non-Prosecuted Application No. 2 127 107, process waste waters of different kinds are obtained, which waste waters are contaminated to a greater or lesser degree. Essentially, process waste waters are an ammonium nitrate solution (NH.sub.4 NO.sub.3) which may also contain carbonates. The starting pH value of the solution is about 7. Such waste waters contain small amounts of uranium, thorium as well as plutonium which may also be considered a uranium daughter substance. The content of uranium, thorium or plutonium is so low that reclaiming of the same is not worthwhile, and decontamination is resorted to. The contamination consists mainly of different uranium isotopes as well as their daughter substances; the latter, in turn, consists predominantly of thorium isotopes. The radiation of the contamination is mainly in the .alpha. and .beta. range.
The problem in the treatment of such radioactive process waste waters is not only to concentrate the contamination contained in these waters and to thereby prepare them for ultimate storage, but also to purify the water in the process to such an extent that it can be discharged without hesitation into the sewer system. The radioactivity value of the treated waters should be below the values prescribed by the radiation protection regulation.